Static pose fixture

ABSTRACT

The present invention relates to a static pose fixture ( 10 ) used for measuring a subject ( 42 ) that is the object of a motion capture system. The static pose fixture ( 10 ) provides a means for holding the subject ( 52 ) in a static position by using various struts in order to automate the sizing of a computer generated model or to position and orient markers with respect to the model.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

FEDERAL RESEARCH STATEMENT

[0002] [Not Applicable]

BACKGROUND OF INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a static pose fixture that isutilized in motion capture systems. More specifically, the presentinvention relates to a static pose fixture utilized to measure geometryand body plate marker locations of a subject for preparation of a motioncapture model during a golf swing.

[0005] 2. Description of the Related Art

[0006] Motion Capture is used to measure the position and or orientationof any object, usually at multiple points in time. There are four maincategories of motion capture devices, mechanical, magnetic, passiveoptical, and active optical. An example of a mechanical device is theCyberglove®. A mechanical device measures the orientation of rigid linksmounted to a subject. A magnetic device such as the AscensionMotionStar® or Polhemus StarTrak® measures the position and orientationof wire coils attached to the subject. Since golf clubs are typicallyconstructed of metal or metal parts, magnetic systems, which may looseaccuracy when metal objects are near by, may experience some distortionduring a golf swing motion measurement. Passive optical systems usemultiple cameras to triangulate the position of reflective markersplaced on the subject. Exemplary examples of a passive optical systemare those made by Vicon and Motion Analysis. Active optical systems usetriangulation to track the position of infrared light emitting diodes.Exemplary examples of active optical systems include systems such asNorthern Digital's Optotrak and Charnwood Dynamics CODA. Active opticalsystems have the ability to distinguish markers from one another, whichgreatly decreases the time it takes to process data and which makes thema preferred device for use with the static pose fixture as describedhowever, any of the devices as previously discussed may be used.

[0007] An active optical motion device is able to determine the positionand orientation of a rigid object as long as 3 non co-linear markers onthat object are in view of the sensors. An occluded marker is a markerthat is not in view of any of the sensors. One marker on a rigid bodyplate is selected to be the origin of a coordinate system. The 3Dposition of each marker on the plate is measured, and the position andorientation of the plate is then reported with respect to the globalorigin. To generate the best possible motion capture data, it isimportant to have more than 3 non co-linear markers on each rigid bodyto increase the chances that at least three markers on the body are notoccluded, since the object itself can come between a marker and asensor.

[0008] To drive a computer generated human model with motion capture,data markers of any type (retro-reflective, active IRED, magnetic,etc.), are mounted on the subject in areas where the motion must beacquired. The subject is then asked to stand straight with arms in ahorizontal position, thus forming a cross with the body. A frame of datais acquired in the form of a point cloud. Within the software, theoperator then moves the human model into the point cloud so that eachmarker is near the same location within the model as on the subject. Ifthe subject has not assumed the exact same posture as the defaultposture of the model, the operator rotates the limbs to mimic thesubject's posture. If the subject is a different size compared to themodel, the operator lengthens or shortens each limb so that it lookscorrect. Once the model is sized and oriented properly within the pointcloud, the configuration is saved and any further motion data acquiredfrom the subject can be used to drive the motion of the model. Somehuman modeling software allows the user to measure body segments andinput values, which can increase accuracy but is relatively timeconsuming.

[0009] Several methods of capturing motion data have been proposedincluding Nesbit et al., U.S. Pat. No. 5,772,522, which discloses theanalysis and measurement of a representative model during an activemotion such as a golf swing.

[0010] Further examples include Kramer, U.S. Pat. Nos. 5,592,401 and6,148,280, which disclose the use of sensor devices placed on a subjectduring an active motion, like a golf swing, thereby enabling the captureand analysis of the motion.

[0011] Still more examples include Haas et al., U.S. Pat. No. 4,137,566,which discloses the use of a plurality of reflective sources and a datacollector to record active motions, like golf swings, for analysis.Mann, U.S. Pat. No. 4,891,748, discloses using video images inpreparation of computer generated models.

[0012] However, the process of sizing and orienting the model in thepoint cloud is time consuming and inaccurate. Because the orientation ofeach limb in space is estimated by the operator, it is subject tovariation and inaccuracy. If it is assumed that the subject is standingwith arms perfectly horizontal when the arms are actually skewedslightly or bent, the location of markers on the wrists of the subjectwill be modeled with a high degree of inaccuracy. As motion capture datais used to drive the model, this inaccuracy will cause the wrist to bedriven to a location that is offset from the measured location. Whenmodeling a golf swing, even slight inaccuracy in the wrists can lead tolarge inaccuracy in the location of the club head, rendering the modelfar less useful. Additionally, if any of the markers move with respectto the subject once the model generation is complete, the process mustbe repeated from the beginning or further inaccuracy will result.

SUMMARY OF INVENTION

[0013] The present invention provides a fixture for holding a motioncapture subject in a static position in order to automate themeasurements of geometry and marker locations. In using motion capturefor swing modeling, it is critical to accurately depict the subject thatis the object of the motion capture. By using the static pose fixture,the subject is constrained to a static position enabling the pre setbody plates to be measured for accurate joint segment length, body angledepiction and body orientation measurements to be used to accuratelydepict on the model of the motion capture subject.

[0014] Furthermore, the present invention enables a technician to makeaccurate repeatable measurements and eliminates a vast number of stepspreviously required to perform the measurements and removes variablesthat typically lead to inaccuracy in designing computer generated modelsused in motion capture. By identifying and measuring body platelocations of the subject while in the static pose fixture, the staticpose fixture also provides a means to automatically position and orientmotion agents corresponding to the body plate locations on the model forachieving accurate repeatable subject data.

[0015] Moreover, if a body plate moves during the modeling process asoften happens, the static pose fixture provides a means to rapidly andautomatically re-position the subject's body plate location formeasuring segment length, body angle or body orientation, whereaswithout the static pose fixture, the entire marker orienting processneeds to be repeated from the beginning.

[0016] Having briefly described the present invention, the above andfurther objects, features and advantages thereof will be recognized bythose skilled in the pertinent art from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0017]FIG. 1 is a perspective view of the static pose fixture of thepresent invention.

[0018]FIG. 2 is a back plan view of the static pose fixture of thepresent invention.

[0019]FIG. 3 is a side plan view of the static pose fixture of thepresent invention.

[0020]FIG. 4 is a front view of a subject with attached body plates inthe static pose fixture.

[0021]FIG. 5 is a side view of a subject with body plates attached inthe static pose fixture.

[0022]FIG. 6 is a perspective view of an alternative embodiment of thestatic pose fixture as described herein.

[0023]FIG. 7 is an illustrative example of an exemplary grip as used onthe static pose fixture.

[0024]FIG. 8 is an illustrative example of a body plate with marker formeasuring the position and orientation of the subject's limbs while inthe static pose fixture.

[0025]FIG. 9 is an illustrative example of a slider with marker fortaking joint center measurements.

[0026]FIG. 10 is an illustrative example of a joint center measurementtaken using a digitizing probe.

[0027]FIG. 11 is a graph of the computer modeling process using thestatic pose fixture as described.

[0028]FIG. 12 is a front view of a computer generated model in thestatic pose posture with motion agents applied.

[0029]FIG. 13 is a side view of a computer generated model in the staticpose posture with motion agents applied.

[0030]FIG. 14 is a view of a computer generated model in ball addressposition as modeled using the static pose fixture.

[0031]FIG. 15 is an example of a computer generated model steppingthrough swing data generated by the computer program using themeasurements established while in the static pose fixture and clubselection data.

DETAILED DESCRIPTION

[0032] As illustrated in FIG. 1, a static pose fixture for measuring thesize of a motion capture subject 52 is generally designated 10. Thestatic pose fixture 10 of the present invention includes a base 12,first and second foot alignment struts 16 and 18, first and secondvertical struts 20 and 22, first and second grips 26 and 28 and firstand second slider struts 30 and 32.

[0033] The base 12 is preferably substantially flat. The base 12preferably has a plurality of wheels 14, to provide the fixture 10 withmobility.

[0034] As illustrated in FIGS. 1-3, first and second foot alignmentstruts 16 and 18 for placement of a right and left foot of a subject 52are located on the upper exterior portion of the base 12. The first andsecond foot alignment struts 16 and 18 are preferably placed at least 4inches from the rear portion of the base 12. The distance d between thefirst foot alignment strut 16 and the second foot alignment strut 18 ispreferably between 10 inches and 18 inches, more preferably from 10inches to 14 inches and most preferably 12 inches to allow the feet ofthe subject 52 to be properly positioned while in the static posefixture 10. The width of the first and second foot alignment struts 16and 18 is preferably 1 inch to 3 inches, more preferably 1.5 inches to2.5 inches and most preferably 2 inches. The first and second footalignment struts are preferably at least 1 inch in thickness and areattached to the base 12 of the static pose fixture 10 using screws, nutand bolt, or any other well-known means thus enabling adjustment of thefirst and second foot alignment struts 16 and 18.

[0035] Each of a first vertical strut 20 and a second vertical strut 22are attached to the upper exterior portion of the base 12 at one end ofthe strut length. The first and second vertical struts 20 and 22 arepreferably parallel to each other and placed at least 4 inches from therear portion of the base. The first and second vertical struts 20 and 22are attached to the base using a nut and bolt, screw or any other wellknown fastening means. The vertical struts 20 and 22 are preferably atleast 66 inches in length and extend substantially perpendicularly upfrom the base 12 along the length of the strut. The first vertical strut20 is located on the outer exterior portion of the first foot alignmentstrut 16 and the second vertical strut 22 is located on the outerexterior portion of the second foot alignment strut 18. The distance d′between the first and second vertical struts 20 and 22 is at least 12inches to support the subject 52 in an upright and comfortable position.Additionally, the first and second vertical struts 20 and 22 arepreferably between 2 inches and 8 inches in width, more preferably 3inches to 6 inches and most preferably 4 inches in width to providestructural stability. The first and second vertical struts 20 and 22 arealso preferably 1 inch to 4 inches in thickness, more preferably 1 inchto 3 inches and most preferably 2 inches.

[0036] A lower back strut, 24 is preferably located at least 30 inchesabove the upper exterior surface of the base 12 in a horizontal planebetwee the first and second vertical struts, 20 and 22 to furtherstabilize the subject 52 while in the static pose fixture 10. The lowerback strut 24 should preferably extend at least 15 inches in length forattachment to the first and second vertical struts 20 and 22 at each endand should preferably be at least 2 inches in width and preferably atleast 1 inch in thickness to provide support for the back of the subject52. The lower back strut 24 may optionally include a strap, belt orother device for locking the subject 52 in place during the measurement.

[0037] As illustrated in FIGS. 1 and. 7, a first grip 26 is attached tothe first vertical strut 20 using a first slider strut 30 on an exteriorportion. A second grip 28 is attached to the second vertical strut 22using a second slider strut 32 along the exterior portion.

[0038] The first and second grips 26 and 28 are substantiallyperpendicular to the first and second vertical struts 20 and 22 andsubstantially parallel to the base 12. The slider struts 30 and 32permit the first and second grips 26 and 28 to move vertically along thelength of the first and second vertical struts 20 and 22. The first andsecond slider struts 30 and 32, are attached to the first and secondvertical struts 20 and 22 with a linear bearing (not shown), however anymethod that allows the strut to slide up and down may be used includingnut and bolt, screw attachment, slide lock and key, bands, pulleys, orlevers. The first and second grips 26 and 28 are preferably positionedat least 15 inches above the base 12. The distance between the first andsecond grips 26 and 28 is between 18 inches and 36 inches, preferablybetween 20 inches and 32 inches and most preferably between 21 inchesand 30 inches. The first and second grips 26 and 28 may be covered tocushion the subject's 52 hands by neoprene, fabric, rubber, foam orother well-known materials to provide cushioning support.

[0039] Alternatively, as illustrated in FIG. 6, the static pose fixture10 has first and second upper arm supports 34 and 36, in place of thefirst and second grips 26 and 28, thereby supporting the left and rightarms of the subject 52 during the measuring process. The first andsecond upper arm supports 34 and 36 are attached to the rear portion offirst and second arm alignment struts 40 and 42. The first and secondupper arm supports 34 and 36 are attached to each of the first andsecond vertical struts 20 and 22 a distance of at least 40 inches fromthe base 12. The first upper support 34 has a right end extendinglaterally outward from the first vertical strut 20 and the second upperarm support 36 has a left end extending laterally outward from thesecond vertical strut 22. At least one linear bearing 38 is located onthe first and second upper arm supports 34 and 36 to allow the first andsecond upper arm supports 34 and 36 to move up and down along the lengthof the first and second vertical strut 20 and 22 to support a subject 52of any size in the proper orientation. The linear bearing 38 should notallow the first and second upper arm supports 34 and 36 to sag, as themeasurements are dependent on the arms being in a parallel 90° anglewith respect to the subject's 52 body.

[0040] The first arm alignment strut 40 is preferably substantiallyperpendicular to the first upper arm support 34 at a right end and thesecond arm alignment strut 42 is preferably substantially perpendicularto the second upper arm support 36 at a left end. The first and secondarm alignment struts 40 and 42 are in relation to each other along anelongated strut 44 which is attached to the rear portion of the firstand second vertical struts 20 and 22 and also attached to the first andsecond arm alignment struts 40 and 42 at a right end for the first armalignment strut 40 and a left end for the second arm alignment strut 42.The elongated strut 44 is preferably located at least 40 inches upwardfrom the base 12 and is preferably at least 18 inches in length. A headand upper back support 46 is attached to the elongated strut 44 at amid-point. The head and upper back support 46 extends substantiallyperpendicularly away from the elongated strut 44 to an unattached end.The head and back support 46 is preferably at least 12 inches in lengthand 3 inches in width to comfortably support the subject's back and headin a steady state position during the measuring process.

[0041] The static pose fixture 10 preferably contains at least twosliders 48, located on any of the first and second vertical struts 20and 22, first and second foot alignment struts 16 and 18, oralternatively on any of the first and second upper arm supports 34 and36, first and second arm alignment struts 40 and 42, and head and upperback support 46.

[0042] As illustrated in FIG. 9, the slider 48, is preferably composedof aluminum, aluminum alloy, composite, steel, or other material. Theslider 48 is preferably shaped in a rectangular or block formation,however it is not limited to this formation. The slider 48 contains atleast one reflective means 50 bonded to it. The reflective means 50 ispreferably bonded to the slider 48 using epoxy, solder, or otherwell-known means. The slider 48 moves freely along the length of thestrut along grooves 49 located in the strut length. The slider 48 isadjusted along the length of the strut using a nut and bold, hex and keyor any other well-known means. One slider 48 is preferably aligned witha major joint segment of a subject's 52 body, while another slider 48 isaligned with a different joint segment of the subject's body therebyincreasing the accuracy of determining the length between the subject's52 limbs by calculating the distance between two sliders 48.

[0043] The static pose fixture 10 is preferably constructed of aluminum,aluminum alloy, steel, or other material providing the requisitesturdiness to support the subject 52 during the modeling process.Extruded aluminum is most preferable as it provides the optimum weightand durability required.

[0044] As illustrated in FIG. 8, to optimize motion capture modelingusing the static pose fixture 10, a subject 52 is placed in a markerinterface suit. This step involves attaching at least one body plate 58to the subject 52 at various joint locations. The body plate ispreferably attached to the subject 52 using clamps, elastic bands,straps, clasps, hook and loop closures or any other well-known means. Apreferred method involves wrapping lengths of stretch fabric around eachlimb of the subject 52. An exemplary stretch fabric for this purpose isVelstretch®. Subsequently, at least one body plate 58 is attached to thestretch fabric using epoxy, snaps, velcro, or any other suitable meansof attachment. The body plate 58 may also optionally be cushionedagainst the subject's 52 limbs by attaching or placing rubber, foam,cloth, or any other material that provides cushioning effect to orbetween the body plate 58 and the subject's 52 limb.

[0045] The body plate 58 is preferably composed of rubber, plastic,composite or ceramic, as shown in FIG. 8, the body plate 58 of thepresent invention is preferably composed of a composite material. Thecomposite material reduces the mass of the body plate 58, whileproviding a stable base for mounting on the subject. Additionally, thecomposite material is preferably molded to provide a curved body plate58 permitting better positioning of the body plate 58 on the subject's52 limbs. It is preferable to use curved body plates 58 for thispurpose, however the body plates 58 are not limited to a curvedconfiguration. The body plate 58 preferably ranges from 0.50 inch to 3.0inches in width, 2.0 inches to 9.0 inches in length and 0.10 inch to 1.0inch in height. The body plate 58 also preferably contains at leastthree markers 60 a-c, but may contain as many as 15-20 markers formeasuring the location of the body plate 58 on the subject 52. Thesemarkers 60 a-c are preferably retro-reflective, active IRED, ormagnetic, but are not limited to these types. As illustrated in FIG. 8,one marker 60 in a body plate 58 is selected to be the origin of alocalized coordinate system. The 3D position of each marker 60 on thebody plate 58 is measured, and the position and orientation of the bodyplate 58 is then reported with respect to a global origin. Additionally,at least one marker 60 is located on the base 12 of the static posefixture 10 to act as an origin point for the localized coordinate systemin the event that one of the markers 60 on the body plate 58 isobscured. The body plate 58 is then connected to a strobe box (notshown), which controls the marker 60 illumination. The use of a curvedbody plate 58 in conjunction with at least three markers 60 a-c on thebody plate 58 alleviates the event of complete marker occlusion thusinsuring that at least one body plate marker 60 will be visible.

[0046] Once the body plate 58 has been attached to the subject 52, thebody plate 58 locations are then optimized on the subject 52. With amotion capture system active, the subject 52 swings a golf club 62 andthe data quality is evaluated by examining a chart of missing data. Ifless than three body plate markers 60 a-c on a body plate 58 are inview, the system will generate no data for the body plate 58 at thatinstant. It is important that fast moving body plates 58 such as thoseon the arms are not occluded for more than 3 consecutive frames duringthe downswing or accuracy will be lost when the missing data isinterpolated. If this occurs, body plates 58 that are occludedexcessively are preferably moved slightly, the subject 52 then swingsagain, and the data quality is evaluated. This process is repeated untilbody plate 58 locations have been optimized.

[0047] As illustrated in FIGS. 4 and 5, once the body plate 58 locationshave been optimized, the subject 52 is then placed in the static posefixture 10. The subject 52 is constrained to a static position andorientation for measurement of the geometry and marker location.

[0048] Joint center measurements are preferably obtained while thesubject 52 is in the static pose fixture 10 by using a digitizing probe56 as illustrated in FIG. 10. By the subject's 52 arms point down andthe hands wrap around the first and second grips 26 and 28 near thesubject's 52 hips. A digitizing probe 56 is preferably used to measurethe distance between various joint segment lengths including thesubject's wrist joints, which are often difficult to measure. Anexemplary digitizing probe is manufactured by Northern Digital, whichmeasures the position of the probe tip with respect to a selectedobject. The probe 56 is preferably used to mark at least four locationson a subject's 52 body thereby recording the position and orientation ofvarious joint segments on the subject's 52 body with respect toposition, providing positional coordinates and angularity, which ispreferably used to set a coordinate system with respect to the globalorigin. A computer program calculates the length and orientation of eachbody segment from the digitizing probe measurements, to build thecomputer model 64 of the subject 52. Additionally, for more precisemeasurements while the subject 52 is in the static pose fixture 10, theposition and orientation of each of the rigid body plates 58 on thesubject 52 is preferably measured and recorded.

[0049] Alternatively, joint center measurements are obtained when thearms are positioned shoulder height and the elbows are bent at 90°degree angles away from the body. The linear bearing 38 on the first andsecond arm alignment struts 40 and 42 are raised or lowered so that thearms rest horizontally. The linear bearing 38 on the first and secondarm alignment struts 40 and 42 nearest the elbows of the subject 52 arethen moved toward or away from the shoulders so that the elbows restagainst the first and second arm alignment struts 40 and 42. A slider 48with at least one means 50 bonded to it is then placed on the first andsecond arm alignment struts 40 and 42 corresponding to each major jointcenter on the subject's 52 arms. A slider 48 is also placed on the firstand second vertical struts 20 and 22, first and second foot alignmentstruts 16 and 18, first and second arm supports 34 and 36 and head andupper back support 46. The slider 48 is adjusted to align with theappropriate joint center and locked in place. A motion capture system isthen used to measure the 3D coordinates of the sliders 48, as well asthe position and orientation of each of the rigid body plates 58 mountedto the subject 52. The distance between two sliders 48, such as thosealigned with the wrist and elbow is calculated and the result is thelength of the corresponding limb, in this case, the forearm. The lengthof each limb is determined by the computer, which calculates thedistance between sliders 48. These lengths are then used to properlysize segment lengths in the computer generated player model 64. The bodyplate 58 position and orientation data is used later to locate themotion agents on the swing model 64 and the measurements are later runinto a computer program that calculates the length and orientation ofeach body segment, to build the computer model 64 of the subject 52. Amodel 64 is preferably built with limb lengths based on the slider 48measurements and limb orientations assumed to be either 0° or 90°.Furthermore, using the rigid body plate 58 measurements obtained whilein the static pose fixture 10, each of the limbs and limb angles will bein the correct position and orientation for the motion capture program.

[0050] Once the measurements have been determined, swing motion ispreferably captured using a motion capture system and any experimentinvolving measuring the swing motion of a player. If at any time thebody plates 58 move on the subject's 52 body, the subject 52 canre-enter the static pose fixture 10 and a new frame of data ispreferably collected. The use of the static pose fixture 10 makesresetting the body plate 58 locations less time consuming and moreaccurate then was previously available by allowing the subject 52 merelyto re-enter the static pose fixture 10, re-set in the known position andrealign the body plates 58. Additionally, the slider 48, which hasalready been locked in place for the subject 52, is preferably used tore-align the subject 52 according to the pre-set slider 48 positions.

[0051] As illustrated in the graph of FIG. 11, during the capture ofswing data, each swing is post-processed using computer programmingsoftware that fits plate position and orientation with a polynomialcurve in order to fill in any gaps in data that is missing due to anoccluded marker 60. An exemplary computer programming software packagefor data is MATLAB® software.

[0052] Next, a player model 64 is built using the measurement dataobtained while the subject 52 was constrained in the static pose fixture10. Various computer software packages are preferably used to build aplayer model 64; one exemplary program is the ADAMS FIGMOD® softwarepackage. To build a player model 64, the height, weight and age of thesubject 52 is entered. The software uses this information to build aplayer model 64 with average mass properties based on an anthropomorphicdatabase.

[0053] Next a file with the limb length and orientation data and bodyplate 58 position and orientation data previously collected is imported.The software uses the limb length data to automatically size each of themodel's 64 limbs.

[0054] Next the computerized player model 64 is brought into the staticpose fixture 10 posture. In this step, each of the model's 64 jointangles is adjusted to the same angles that were measured on the subject52 while in the Static Pose Fixture 10. Each limb of the model 64 nowoccupies the same space in the model 64 coordinate system as it did inthe measurement coordinate system.

[0055] As illustrated in FIGS. 12 and 13, motion agents are applied tothe model 64 while in the static pose posture. Illustrative spheresrepresenting origins of each of the rigid body plates 58 are linked toeach limb of the model 64 as measured using the static pose fixture 10.Later, minimizing the distances and angles between the data points andthe motion agents will control the model's 64 motion. With the model 64correctly sized and oriented in previous steps, motion agents are simplyloaded into space in the position and orientation measured while theplayer was in the static pose fixture 10. Each agent is then rigidlylinked to its corresponding limb.

[0056] The joint angles and limbs as defined by the body plate 58locations of the player model 64 are rotated to bring the player into apose that is similar to a typical ball address position as illustratedin FIG. 14. This will make it easier for the software to bring theplayer into the measured address position later.

[0057] Previously collected swing data is then imported and the firstframe of data with the player in the address position is loaded into thesoftware program.

[0058] Once the swing data is set, the computer program performs astatic analysis to minimize the distance between the motion agents andthe data points in the first frame of data. This brings the player model64 into the measured address position.

[0059] Additionally, position data points obtained using the digitalprobe 56 are preferably loaded into the program. These points will showup in space in the same location as previously measured. Points on theaxes of the model's 64 joint segments are moved to the measured jointsegment points and locked in those locations. In addition, difficult tomeasure wrist data is incorporated into the program through measurementsobtained using the digital probe.

[0060] A club 62 is preferably selected for the player model 64 and aparametric model of the golf club 62 can be loaded and gripped by theplayer model 64. The selection of a particular club 62 allows theaffects that various club properties have on a player's swing to beevaluated as well as the performance of various products for aparticular swing.

[0061] Once the club 62 has been selected and assigned to the playermodel 64, the swing model is actuated. The player model 64 is preferablyshown as a computer-generated model 64 or in a more animated form asillustrated in FIG. 15. The swing model allows the program to stepthrough the swing data frame by frame and maintain the minimum distancebetween the data points and motion agents. Effectively, this step causesthe model 64 to reproduce the actual swing with a high degree ofaccuracy.

[0062] Additionally, joint torque values are determined using inversedynamics, as performed in the ADAMS FIGMOD® program to calculates thetorque produced by each joint throughout the swing based on the swingmotion and mass and size properties of the player's limbs. Once thejoint torque values are assigned, the model 64 applies the joint torquevalues to the player model 64 through time, rather than minimizing thedistance between motion agents and data points. In this mode, clubproperties can be varied, and the affects of these variables on swingmotion can be studied.

[0063] From the foregoing it is believed that those skilled in thepertinent art will recognize the meritorious advancement of thisinvention and will readily understand that while the present inventionhas been described in association with a preferred embodiment thereof,and other embodiments illustrated in the accompanying drawings, numerouschanges, modifications and substitutions of equivalents is preferablymade therein without departing from the spirit and scope of thisinvention which is intended to be unlimited by the foregoing except asmay appear in the following appended claims. Therefore, the embodimentsof the invention in which an exclusive property or privilege is claimedare defined in the following appended claims.

We claim as our invention:
 1. A static pose fixture for measuring aperson who is a subject of a motion capture model, the fixturecomprising: a base having a substantially flat surface; at least onemarker; a pair of foot alignment struts located on the upper rearsurface of the base wherein the distance between a first foot alignmentstrut and a second foot alignment strut is at least 10.0 inches; a pairof vertical struts located on the upper rear surface of the base whereina first vertical strut is located on an outer exterior portion of thefirst foot alignment strut and a second vertical strut is located on anouter exterior portion of the second foot alignment strut; and a pair ofgrips attached to the pair of vertical struts and located at least 15inches above the base.
 2. The static pose fixture according to claim 1further comprising a lower back strut located at least 30 inches abovethe upper surface of the base.
 3. The static pose fixture according toclaim 1 further comprising at least two sliders with markers located onat least one of the first vertical strut, second vertical strut, firstfoot alignment strut and second foot alignment strut.
 4. The static posefixture according to claim 1 wherein the at least one marker is locatedon the base.
 5. The static pose fixture according to claim 1 wherein thefixture is comprised of aluminum.
 6. A static pose fixture for measuringa subject who is an object of a motion capture model, the fixturecomprising: a base; at least one marker; a first vertical strut and asecond vertical strut extending upward from the base a distance of atleast 66.0 inches; a first upper arm support and a second upper armsupport attached to each of the first and second vertical struts; afirst arm alignment strut attached to and substantially perpendicular tothe upper arm support at the right end of the upper arm support, and asecond arm alignment strut attached to and substantially perpendicularto the upper arm support at the left end of the upper arm support; anelongated strut attached to the rear portion of the first and secondvertical struts; and a head and upper back support attached to theelongated strut at a mid-point.
 7. The static pose fixture according toclaim 6 further comprising first and second foot alignment struts. 8.The static pose fixture according to claim 6 wherein at least one linearbearing is located on the first and second arm supports.
 9. The staticpose fixture according to claim 6 further comprising at least twosliders with markers located on at least one of the first verticalstrut, second vertical strut, first foot alignment strut, second footalignment strut, first upper arm support, second upper arm support,first arm alignment strut, second arm alignment strut, elongated strutand head and upper back support.
 10. The static pose fixture accordingto claim 6 wherein the at least one marker is located on the base.
 11. Amethod of measuring a subject which is the object of a motion capturemodel using a static pose fixture comprising: attaching at least onebody plate to a subject; optimizing the at least one body platelocations; positioning the subject in the static pose fixture; measuringat least two joint segment lengths of the subject; converting themeasurements into a localized coordinate system; generating a computermodel of the subject based on the measurements.
 12. The method accordingto claim 11 wherein a digitizing probe is used to measure the jointsegment lengths.
 13. The method according to claim 11 wherein thedistance between at least two slider markers are used to measure thejoint segment lengths.
 14. The method according to claim 11 whereincomposite body plates are used.
 15. The method according to claim 14wherein curved body plates are used.
 16. The method according to claim14 wherein body plates with at least 3 markers are used.
 17. A method ofmeasuring a subject, who is an object of a motion capture model using astatic pose fixture comprising: attaching at least one body plate to asubject; positioning the subject in the static pose fixture; measuringthe subject using a digitizing probe; marking at least 4 locations onthe subject's body; recording the position and orientation of each bodysegment marked; converting the measurements into a localized coordinatesystem; generating a computer model of the subject based on themeasurements.